Sintering devices for performing low-temperature pressure sintering of electronic assemblies are already known. Such sintering devices comprise, for example, a sintering chamber which may be filled with a gas which particularly facilitates the sintering operation or a corresponding gas mixture, and an upper die disposed in the sintering chamber and a lower die, the upper die and the lower die being slidable towards one another and preferably each having a dedicated heating unit.
Sintering of the electronic assembly itself takes place by temperature-controlling the assemblies to be sintered and by applying pressure imparted by the dies. In this manner, the temperature required for the connection and diffusion in the case of low-temperature pressure sintering, using silver (Ag), is typically between 130° C. and 250° C. to 300° C., for example, and, at a pressure up to 30 MPa, requires a time duration of around 5 to 10 min.
In sintering, the diffusion process is facilitated, in particular, by silver layers having a large surface between the joining parts, by using either initially fine particles (5 nm to 20 μm) in the form of pasty layers or pre-processed Ag platelets. In order for a particularly shear-resilient and fine closed-porous layer to be created, the joining layer, prior to and during the diffusion process, is compacted by pressure. After the diffusion process subsides, the pressure and the temperature are reduced.
As a result of such a sintering process, a shear-resilient and materially integral connection which electrically and thermally connects the components, e.g. a transistor, with the substrate of the electronic assembly is obtained, wherein the assembly thus processed may be removed from the sintering device after pressure and temperature have been lowered and the dies have been opened.
It is a problem when using pressure pads that these pads, on account of heavy deforming work on the components, sometimes create edge damage. Therefore, it is already known from DE 10 2010 020 696 B4 to mould a pressure pad having a contour which, as a negative, corresponds to the assembly to be sintered.
In turn it is disadvantageous in a pressure pad contoured in such a manner that, while enclosure of the assembly to be sintered is indeed possible, lateral deflection of the pressure pad when high pressures are applied which damage to the assembly cannot be completely avoided.